Organic light emitting diode display

ABSTRACT

There is provided an organic light emitting diode display including: a substrate having a pixel area and a surrounding area enclosing the pixel area; an OLED formed in the pixel area; an anti-overflowing groove formed in the surrounding area of the substrate; and a dam positioned between the anti-overflowing groove and an end of the substrate.

CROSS-REFERENCE TO RELATED APPLICATION APPLICATION(S)

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57. Thisapplication claims priority to and the benefit of Korean PatentApplication No. 10-2015-0007024 filed in the Korean IntellectualProperty Office on Jan. 14, 2015, the entire contents of which areincorporated herein by reference.This application is a reissueapplication of U.S. Pat. No. 9,818,807 issued Nov. 14, 2017, whichissued from U.S. patent application Ser. No. 14/871,867 filed Sep. 30,2015. U.S. Pat. No. 9,818,807 claims priority benefit of Korean PatentApplication No. 10-2015-0007024, filed on Jan. 14, 2015, in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference for all purposes.

BACKGROUND

Field

The present disclosure relates to a display device, and moreparticularly, to an organic light emitting diode display.

Description of the Related Technology

An organic light emitting diode (OLED) display includes a matrix ofOLEDs each configured to include a hole injection electrode, an organicemission layer, and an electron injection electrode. Each OLED emitslight by energy generated when excitons generated by a combination ofelectrons and holes in the organic emission layer drop from an excitedstate to a ground state. OLED technology displays a predetermined imageby careful control of the emitted light.

The organic light emitting diode display has self-luminancecharacteristics and unlike a liquid crystal display, does not need aseparate light source and therefore may have a reduced thickness andweight. Further, the OLED is a display which represents high qualitycharacteristics, such as low power consumption, high luminance, and ahigh response rate and therefore has drawn much attention as anext-generation display device.

OLED display needs a process to protect the pixel by encapsulating thepixel using a glass substrate. However, due to the thickness and weightof the glass substrate, thin film encapsulation (TPE) technology whichalternately stacks an inorganic layer and an organic layer in at leastone layer and encapsulates the laminate has been developed.

The organic layer is applied by a solution process and applied to thedisplay area, and is fluid in nature until is hardened and when it isover-applied, the organic layer overflows out of the display area.

SUMMARY

The present disclosure has been made in an effort to provide an OLEDdisplay having the advantage of minimized overflow of the organicmaterial out of a substrate even though the organic material isover-applied at the time of applying the organic material.

An exemplary embodiment provides an OLED display including: a substratehaving a pixel area and a surrounding area enclosing the pixel area; anorganic light emitting diode formed in the pixel area; ananti-overflowing groove formed in the surrounding area of the substrate;and a dam positioned between the anti-overflowing groove and an end ofthe substrate.

The OLED display may further include: a semiconductor formed in thepixel area; a gate insulating layer formed on the semiconductor and thesubstrate; a gate electrode formed on the gate insulating layer; a firstinterlayer insulating layer formed on the gate electrode and the gateinsulating layer; and a source electrode and a drain electrode formed onthe first interlayer insulating layer, wherein the anti-overflowinggroove is formed through the first interlayer insulating layer andexposes the gate insulating layer.

The OLED display may further include: a buffer layer formed on thesubstrate, wherein the anti-overflowing groove is formed through thefirst interlayer insulating layer and the gate insulating layer andexposes the buffer layer.

The OLED display may further include: a second interlayer insulatinglayer formed on the source electrode and a drain electrode, wherein theOLED includes: a first electrode formed on the second interlayerinsulating layer; an organic light emitting layer formed on the firstelectrode, and a second electrode formed on the organic emission layer.

The OLED display may further include: a pixel defined layer having anopening which is formed on the second interlayer insulating layer andexposes the first electrode, wherein the dam includes a lower layer madeof the same material as the second interlayer insulating layer and anupper layer positioned on the lower layer and made of the same materialas the pixel defined layer.

The dam may include a first dam and a second dam positioned at bothsides, having the anti-overflowing groove disposed there between.

The OLED display may further include: an encapsulation layer positionedon the substrate and covering the pixel area, wherein the encapsulationlayer includes at least one inorganic layer and organic layer.

The OLED display may further include: an anti-crack groove positionedbetween the dam and the end of the substrate.

According to an exemplary embodiment, it is possible to prevent theorganic material from leaking out of the substrate by forming the damand the groove in the surrounding area outside the display area eventhough the organic material overflows at the time of forming the organiclayer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view schematically illustrating an OLED displayaccording to an exemplary embodiment.

FIG. 2 is an equivalent circuit diagram of one pixel of the OLED displayaccording to the exemplary embodiment.

FIG. 3 is an enlarged plan view of portion A of FIG. 1.

FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 3.

FIG. 5 is an enlarged cross-sectional view of an anti-overflowing grooveformed according to an exemplary embodiment.

DETAILED DESCRIPTION

As the disclosure allows for various changes and numerous embodiments,particular embodiments will be illustrated in the drawings and describedin detail in the written description. However, this is not intended tolimit the present disclosure to particular modes of practice, and it isto be appreciated that all changes, equivalents, and substitutes that donot depart from the spirit and technical scope of the present disclosureare encompassed in the present disclosure. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Embodiments of the present disclosure will be described below in moredetail with reference to the accompanying drawings. Those componentsthat are the same or are in correspondence are rendered the samereference numeral regardless of the figure number, and redundantexplanations are omitted.

It will be understood that although the terms “first”, “second”, etc.may be used herein to describe various components, these componentsshould not be limited by these terms. These components are only used todistinguish one component from another.

As used herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

It will be further understood that the terms “comprises” and/or“comprising” used herein specify the presence of stated features orcomponents, but do not preclude the presence or addition of one or moreother features or components.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for explanation. In other words, since sizes andthicknesses of components in the drawings are arbitrarily illustratedfor convenience of explanation, the following embodiments are notlimited thereto. Like reference numerals designate like elementsthroughout the specification. It will be understood that when an elementsuch as a layer, film, region, or substrate is referred to as being “on”another element, it can be directly on the other element or interveningelements may also be present. In contrast, when an element is referredto as being “directly on” another element, there are no interveningelements present.

Hereinafter, an OLED display according to an exemplary embodiment willbe described with reference to the accompanying drawings.

FIG. 1 is a plan view schematically illustrating an OLED displayaccording to an exemplary embodiment nd FIG. 2 is an equivalent circuitdiagram of one pixel of the OLED display according to the exemplaryembodiment

As illustrated in FIG. 1, an OLED display 1000 according to an exemplaryembodiment includes a substrate 100 in which a pixel area PA and asurrounding area SA enclosing the pixel area PA is divided, a pluralityof pixels Ps formed in the pixel area PA of the substrate 100, drivers600 and 700 formed in the surrounding areas SA of the substrate 100 andconnected to the pixels Ps, respectively, and a power supply unit 400.

A plurality of signal lines 121, 171, and 172 which are formed from thesurrounding area SA to the pixel area PA are formed on the substrate 100and the pixels Ps are connected thereto and are arranged approximatelyin a matrix form.

The signal lines 121, 171, and 172 include a plurality of first signallines 121 which transfer gate signals (or scanning signals), a pluralityof second signal lines 171 which transfer data signals, and a pluralityof third signal lines 172 which transfers a driving voltage Vdd. Thefirst signal lines 121 extend in approximately a row direction and areapproximately parallel with each other and the second signal line 171and the third signal line 172 intersect each other with being insulatedfrom the first signal line, extend in a column direction, and areapproximately parallel with each other.

Referring to FIG. 2, each pixel P includes a driving thin filmtransistor Qd, switching thin film transistor Qs, a storage capacitorCst, and an organic light emitting diode (OLED) LD.

The driving thin film transistor Qd also have a control terminal, aninput terminal, and an output terminal, in which the control terminal isconnected to the switching thin film transistor Qs, the input terminalis connected to the third signal line 172, and the output terminal isconnected to the organic light emitting diode (OLED) LD. The drivingthin film transistor Qd transfers an output current I_(LD) of which amagnitude varies depending on a voltage applied between the controlterminal and the output terminal.

The switching thin film transistor Qs also includes a control terminal,an input terminal, and an output terminal, in which the control terminalis connected to the first signal line 121, the input terminal isconnected to the second signal line 171, and the output terminal isconnected to the driving thin film transistor Qd. The switching thinfilm transistor Qs transfers the data signal applied to the secondsignal line 171 to the driving thin film transistor Qd in response tothe scanning signal applied to the first signal line 121.

The storage capacitor Cst is connected between the control terminal andthe input terminal of the driving thin film transistor Qd. The storagecapacitor Cst charges the data signal applied to the control terminal ofthe driving thin film transistor Qd and maintains the charged datasignal even after the switching off the thin film transistor Qs.

The OLED has an anode connected to the output terminal of the drivingthin film transistor Qd and a cathode connected to a common voltage Vss.The organic light emitting diode (OLED) LD displays an image by emittinglight of which the strength varies depending on the output currentI_(LD) of the driving thin film transistor Qd.

Referring again to FIG. 1, the surrounding area SA is provided with aplurality of anti-crack grooves CPs to prevent a crack of the substrate100. The anti-crack grooves CPs are formed along corners of thesubstrate 100 to enclose the pixel area PA and are adjacently positionedto ends of the substrate 100.

Further, the surrounding area SA is provided with at least one dam D1,D2, and D3 to prevent the organic material positioned in the pixel areaPA from overflowing to edges of the substrate. FIG. 1 illustrates thatthree dams are formed but the dam may be formed in one or at least four,if necessary.

The dams D1, D2, and D3 are formed to enclose the pixel area PA and arepositioned between the pixel area PA and the anti-crack groove CP.

Meanwhile, at least one anti-overflowing groove V is formed between thedams D1, D2, and D3 and the pixel area PA. FIG. 1 illustrates that theanti-overflowing groove V is formed between the second dam D2 and thethird dam D3 but the present disclosure is not limited thereto.Therefore, the anti-overflowing groove V may be formed (not illustrated)between the first dam and the pixel area and the first dam and thesecond dam, if necessary.

As such, when the anti-overflowing groove is formed between the dams,even though the organic material overflows the dam positioned in frontof the groove before the organic material forming the encapsulationlayer for protecting the pixel area is hardened, the organic materialflows in the anti-overflowing groove V to prevent the organic materialfrom flowing out of the dam positioned after the anti-overflowing grooveV.

Hereinafter, a laminar structure of the OLED display according to theexemplary embodiment will be described in detail with reference to theaccompanying drawings. In this case, the switching thin film transistorsand the driving thin film transistors of a red pixel PR, a green pixelPG, and a blue pixel PB, respectively, have the same laminar structure,and therefore the driving thin film transistor Qd and the organic lightemitting diode (OLED) LD of the red pixel PR will be described in detaildepending on the stacked order. Hereinafter, the driving thin filmtransistor Qd is referred to as a thin film transistor Q. Further, thesurrounding area of the OLED display may be provided with transistorsand driving circuits of the display area, together. The driving circuitincludes a plurality of signal lines and a plurality of transistors, andtherefore a transistor TS of one circuit unit will be described as anexample.

FIG. 3 is an enlarged plan view of portion A of FIG. 1 and FIG. 4 is across-sectional view taken along the line IV-IV of FIG. 3.

As illustrated in FIGS. 3 and 4, the OLED display 1000 includes thesubstrate 100, in which a buffer layer 120 is formed on the substrate.

The substrate 100 may be made of plastic such as polycarbonate,polyimide, and polyether sulfone, glass, or the like. The substrate maybe a transparent flexible substrate having flexibility, such aselasticity, or the like, which may be folded, bent, rolled, or stretchedin at least one direction.

The buffer layer 120 may have a single layer structure made of siliconnitride (SiNx) or a double layer structure in which silicon nitride(SiNx) and silicon oxide (SiO_(x)) are stacked. The buffer layer 120serves to planarize a surface while preventing permeation of unnecessarycomponents, such as impurities and moisture.

Semiconductors 55 and 135 are formed on the buffer layer 120. Thesemiconductors 55 and 135 may be made of polysilicon or oxidesemiconductor. The oxide semiconductor may include any one of an oxideof titanium (Ti), hafnium (Hf), zirconium (Zr), aluminum (Al), tantalum(Ta), germanium (Ge), zinc (Zn), gallium (Ga), tin (Sn), or indium (In),and an indium-gallium-zinc oxide (InGaZnO₄), an indium-zinc oxide(Zn—In—O), a zinc-tin oxide (Zn—Sn—O), an indium-gallium oxide(In—Ga—O), an indium-tin oxide (In—Sn—O), an indium-zirconium oxide(In—Zr—O), an indium-zirconium-zinc oxide (In—Zr—Zn—O), anindium-zirconium-tin oxide (In—Zr—Sn—O), an indium-zirconium-galliumoxide (In—Zr—Ga—O), an indium-aluminum oxide (In—Al—O), anindium-zinc-aluminum oxide (In—Zn—Al—O), an indium-tin-aluminum oxide(In—Sn—Al—O), an indium-aluminum-gallium oxide (In—Al—Ga—O), anindium-tantalum oxide (In—Ta—O), an indium-tantalum-zinc oxide(In—Ta—Zn—O), an indium-tantalum-tin oxide (In—Ta—Sn—O), anindium-tantalum-gallium oxide (In—Ta—Ga—O), an indium-germanium oxide(In—Ge—O), an indium-germanium-zinc oxide (In—Ge—Zn—O), anindium-germanium-tin oxide (In—Ge—Sn—O), an indium-germanium-galliumoxide (In—Ge—Ga—O), a titanium-indium-zinc oxide (Ti—In—Zn—O), and ahafnium-indium-zinc oxide (Hf—In—Zn—O), which are composite oxidesthereof. When the semiconductors 55 and 135 are made of the oxidesemiconductor, a separate passivation layer may be added to protect theoxide semiconductor which is vulnerable to external environments, suchas high temperature.

The semiconductor 55 and 135 includes channels 55c and 1355 which arechannel-doped with N-type impurity or P-type impurity and source dopingregions 55s and 1356 and drain doping regions 55d and 1357 which areformed at both sides of the channel and have doping concentration higherthan that of impurity with which the channel is doped.

A gate insulating layer 140 is formed on the semiconductors 55 and 135.The gate insulating layer 140 may be a single layer or plural layersincluding at least one of tetraethyl orthosilicate (TEOS), siliconnitride, and silicon oxide.

Gate electrodes 25 and 155 are formed on the semiconductors 55 and 135and the gate electrodes 25 and 155 overlap the channel regions 55c and1355.

The gate electrodes 25 and 155 may be formed of a single layer or plurallayers including low resistance materials such as Al, Ti, Mo, Cu, Ni oran alloy thereof or materials having strong corrosion.

A first interlayer insulating layer 160 is formed on the gate electrodes25 and 155. Like the gate insulating layer 140, the first interlayerinsulating layer 160 may be formed in a single layer or plural layersincluding tetraethyl orthosilicate (TEOS), silicon nitride, siliconoxide, or the like.

The first interlayer insulating layer 160 and the gate insulating layer140 are provided with source contact holes 63 and 66 and drain contactholes 65 and 67 through which the source regions 55s and 1356 and thedrain regions 55d and 1357 are each exposed.

A power terminal 68, source electrodes 73 and 176, and drain electrodes75 and 177 are formed on the first interlayer insulating layer 160.

The power terminal 68 is positioned in a power supply unit 400 and maybe applied with external power.

The source electrodes 73 and 176 each contact the source regions 55s and1356 through the contact holes 63 and 66 and the drain electrodes 75 and177 are each connected to the drain regions 55d and 1357 through thecontact holes 65 and 67.

The source electrodes 73 and 176 and the drain electrodes 75 and 177 maybe formed of a single layer or plural layers including low resistancematerials such as Al, Ti, Mo, Cu, Ni or an alloy thereof or materialshaving strong corrosion resistance. For example, they may be formed in atriple layer of Ti/Cu/Ti, Ti/Ag/Ti, Mo/Al/Mo.

The gate electrodes 25 and 155, the source electrodes 73 and 176, andthe drain electrodes 75 and 177 each are a control electrode, an inputelectrode, and an output electrode of FIG. 3 and form thin filmtransistors TS and Q together with the semiconductors 55 and 135. Thechannel of the thin film transistor is formed in the semiconductor 135between the source electrodes 55s and 176 and the drain electrodes 55dand 177.

A second interlayer insulating layer 180, a lower layer 181 of a seconddam, and a lower layer 182 of a third dam are formed on the sourceelectrodes 73 and 176 and the drain electrodes 75 and 177.

The second interlayer insulating layer 180 includes a contact hole 85through which the drain electrode 177 is exposed and includes theanti-overflowing groove V which is formed in the second interlayerinsulating layer 180, the first interlayer insulating layer 160, and thegate insulating layer 140 to expose the buffer layer 120, and aplurality of anti-crack grooves CPs.

The exemplary embodiment illustrates that the anti-overflowing groove Vis formed up to the gate insulating layer 140 to expose the buffer layer120 but is not limited thereto. Therefore, if necessary, theanti-overflowing groove V may be formed to expose (not illustrated) thegate insulating layer 140 or the first interlayer insulating layer 160.

The anti-crack groove CP is to prevent a crack of the inorganic layerwhich is relatively vulnerable to crack and the anti-crack groove CP ispreferably formed on a layer formed of an inorganic layer among the gateinsulating layer or the interlayer insulating layer.

Like the first interlayer insulating layer 140, the second interlayerinsulating layer 180 may be formed in a single layer or plural layersincluding tetraethyl orthosilicate (TEOS), silicon nitride, siliconoxide, or the like and may be made of a low-permittivity organicmaterial.

The lower layer 181 of the second dam and the lower layer 182 of thethird dam may be made of the same material as the second interlayerinsulating layer 180 together.

A connecting member 70 and a first electrode 710 are formed on thesecond interlayer insulating layer 180.

The first electrode 710 is electrically connected to the drain electrode177 through the contact hole 85 and the first electrode 710 may be ananode of the OLED of FIG. 3.

The connecting member 70 is connected to the power terminal 68 through acontact hole 42.

According to the exemplary embodiment, the interlayer insulating layeris formed between the first electrode 710 and the drain electrode 177,but the first electrode 710 may be formed on the same layer as the drainelectrode 177 and may be integrated with the drain electrode 177.

A pixel defined layer 190 is formed on the first electrode 710 and afirst dam D1 is formed on the connecting member 70. An upper layer 191of the second dam is formed on the lower layer 181 of the second dam andan upper layer 192 of the third dam is formed on the lower layer 182 ofthe third dam.

The pixel defined layer 190 has an opening 95 through which the firstelectrode 710 is exposed. The pixel defined layer 190 may be made ofresin such as polyacrylates or polyimides, silica-based inorganicmaterials, and the like.

The first dam D1, the upper layer 191 of the second dam, and the upperlayer 192 of the third dam pixel may be made of the same material as thepixel defined layer 190 and the first dam D1 may overlap some of theconnecting member 70.

An organic light emitting layer 720 is formed on the opening 190 of thepixel defined layer 95.

The organic light emitting layer is formed of a plurality of layerswhich include at least one of a light emitting layer, a hole-injectionlayer (HIL), a hole-transporting layer (HTL), an electron-transportinglayer (ETL), and an electron-injection layer (EIL).

When the organic light emitting layer 720 includes both of them, thehole injection layer is disposed on the first electrode 710 which is theanode and the hole transport layer, the light emitting layer, theelectron transport layer, and the electron injection layer may bestacked thereon.

The emission layer 720 may include a red emission layer which emits redlight, a green emission layer which emits green light, and a blueemission layer which emits blue light, in which the red emission layer,the green emission layer, and the blue emission layer are each formed ina red pixel, a green pixel, and a blue pixel to implement a color image.

Further, the emission layer 720 may be formed by stacking the redemission layer, the green emission layer, and the blue emission layer inall of the red pixel, the green pixel, and the blue pixel and forming ared color filter, a green color filter, and a blue color filter for eachpixel to implement a color image. As another example, the color imagemay be implemented by forming a white emission layer which emits whitelight in all of the red pixel, the green pixel, and the blue pixel andforming the red color filter, the green color filter, and the blue colorfilter for each pixel. At the time of implementing the color image usingthe white emission layer and the color filters, there is no need to usea deposition mask for depositing the red emission layer, the greenemission layer, and the blue emission layer on each pixel, that is, thered pixel, the green pixel, and the blue pixel.

Further, the white emission layer may be formed of one emission layerwhich emits white light and the emission layer which emits light of aplurality of different colors may be stacked to emit white light. Forexample, the white emission layer may also include a configuration toemit white light by combining at least one yellow emission layer with atleast one blue emission layer, a configuration to emit white light bycombining at least one cyan emission layer with at least one redemission layer, and a configuration to emit white light by combining atleast one magenta emission layer with at least one green emission layer,and the like.

The second electrode 730 which is a cathode of FIG. 2 is formed on thepixel defined layer 190 and the organic emission layer 720.

The first electrode 710, the organic emission layer 720, and the secondelectrode 730 form the organic light emitting diode LD.

The OLED display may have any one structure of a front display type, arear display type, a double-sided display type depending on a directionin which the organic light emitting diode (OLED) LD emits light.

In the case of the front display type, the first electrode 710 is formedof a reflective layer and the second electrode 730 is formed of atransflective layer or a transparent layer. On the other hand, in thecase of the rear display type, the first electrode 710 is formed of atransflective layer and the second electrode 730 is formed of areflective layer. Further, in the case of the double-sided display type,the first electrode 710 and the second electrode 730 are formed of atransparent layer or a transflective layer.

The reflective layer and the transflective layer are made of at leastone metal of magnesium (Mg), silver (Ag), gold (Au), calcium (Ca),lithium (Li), chromium (Cr), and aluminum (Al) or an alloy thereof. Thereflective layer and the transflective layer are determined as athickness and the transflective layer may be formed of a thickness of200 nm or less. The thickness is inversely proportional to thetransmittance of light and inversely proportional to the resistance.

The transparent layer is made of materials such as indium tin oxide(ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and indium oxide(In₂O₃).

The second electrode 730 may be applied with a cathode voltage throughthe connecting member 70 which is connected to the power terminal 68.

An encapsulation layer 260 is formed on the second electrode.

At least one organic layer and at least one inorganic layer mayalternate each other to form the encapsulation layer 260. The inorganiclayer or the organic layer may be each formed in plural and FIG. 4illustrates that two inorganic layers 22 and 24 and two organic layers21 and 23 are formed.

The organic layers 21 and 23 may be formed of polymer, and may be,preferably, a single film or a stacked film formed of any one ofpolyethylene terephthalate, polyimide, polycarbonate, epoxy,polyethylene, and polyacrylate. More preferably, the organic layer maybe formed of polyacrylate. Therefore, the organic layer may include apolymerized monomer composition including a diacrylate based monomer anda triacrylate based monomer. A monoacrylate-based monomer may further beincluded in a monomer composition,

Further, a known photo initiator such as TPO may be further included inthe monomer composition but is not limited thereto.

The inorganic layers 22 and 24 may be a single layer or a stacked layerincluding metal oxide or metal nitride. Therefore, the inorganic layermay include any one of SiNx, Al₂O₃, SiO₂, and TiO₂.

An uppermost layer exposed to the outside in the encapsulation layer maybe the organic layer to prevent moisture from being permeated into theOLED.

The encapsulation layer may include at least one sandwich structure inwhich at least one organic layer is inserted between at least twoinorganic layers.

The encapsulation layer may sequentially include a first inorganiclayer, a first organic layer, and a second inorganic layer from thesecond electrode of the OLED. Further, the encapsulation layer maysequentially include the first inorganic layer, the first organic layer,the second inorganic layer, the second organic layer, and a thirdinorganic layer from the second electrode. Further, the encapsulationlayer may sequentially include the first inorganic layer, the firstorganic layer, the second inorganic layer, the second organic layer, thethird inorganic layer, and a third organic layer, and a fourth inorganiclayer from the upper portion of the second electrode.

A metal halide layer including LiF may be further included between thesecond electrode and the first inorganic layer. The metal halide layerprevents the OLED including the second electrode from being damaged whenthe first inorganic layer is formed by a sputtering method or a plasmadeposition method.

The first organic layer may have an area narrower than that of thesecond inorganic layer and the second organic layer may have an areanarrower than that of the third inorganic layer. Therefore, the firstorganic layer may be completely covered with the second inorganic layerand the second organic layer may be completely covered with the thirdinorganic layer. Therefore, an end of the lower layer which ispositioned under an upper layer is not exposed by the upper layer whichis positioned above the lower layer.

Meanwhile, according to the exemplary embodiment, when theanti-overflowing groove is formed, it is possible to prevent the organicmaterial from overflowing to the edge of the substrate at the time offorming the organic layer.

This will be described below in detail with reference to FIG. 5.

FIG. 5 is an enlarged cross-sectional view of an anti-overflowing grooveformed according to an exemplary embodiment.

As illustrated in FIG. 5, the first inorganic layer 22 is formed on thesubstrate 100 and the organic material is applied on the inorganic layer22 to form the second organic layer 23. The organic material moves tothe edges of the substrate before being hardened and is spread. In thiscase, when the organic material is over-applied, the organic materialoverflows the first dam D1 and the dam D2 and thus flows in theanti-overflowing groove V.

Since the over-applied organic material fills the anti-overflowinggroove V and then overflows the third dam D3, most of the organicmaterial overflowing the second dam D2 is stored in the anti-overflowinggroove V and therefore does not overflow the third dam D3.

Therefore, the height of the third dam D3 rises along with the depth ofthe anti-overflowing groove V due to the anti-overflowing groove V, andtherefore the organic material hardly overflows the third dam D3.

As such, according to the exemplary embodiment, the anti-overflowinggroove is formed, and thus the height of the third dam may be increasedwithout further forming the dam, thereby easily preventing theoverflowing of the organic material.

The foregoing exemplary embodiments describe only the second organiclayer 23, but are not limited thereto. Therefore, it may be expectedthat the same effect may be obtained even by the additionally formedorganic layer (not illustrated) after the first organic layer (notillustrated) and the second inorganic layer 24 are formed.

It should be understood that the exemplary embodiments described thereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

While one or more embodiments of the present disclosure have beendescribed with reference to the figures, it will be understood by thoseof ordinary skill in the art that various changes in form and detailsmay be made therein without departing from the spirit and scope of thepresent disclosure as defined by the following claims.

What is claimed is:
 1. An OLED display, comprising: a flexible substratehaving a pixel area; a semiconductor layer formed in the pixel area anddisposed on the flexible substrate; a substrate having a pixel area anda surrounding area enclosing the pixel area; an OLED formed in the pixelarea; an anti-overflowing groove formed in the surrounding area of thesubstrate; and a dam positioned between the anti-overflowing groove andan end of the substrate, a semiconductor formed in the pixel area; agate insulating layer formed disposed on the semiconductor and thesubstrate; a gate electrode formed disposed on the gate insulatinglayer; a first interlayer insulating layer formed disposed on the gateelectrode and the gate insulating layer; a source electrode and a drainelectrode formed disposed on the first interlayer insulating layer; asecond interlayer insulating layer formed disposed on the sourceelectrode and a the drain electrode; and a first electrode electricallyconnected to the drain electrode on the second interlayer insulatinglayer; a pixel defined layer having an opening which is formed anddisposed on the second interlayer insulating layer and exposes exposingthe first electrode,; wherein the anti-overflowing groove is formedthrough the first interlayer insulating layer and exposes the gateinsulating layer, wherein the OLED includes: a first electrode formed onthe second interlayer insulating layer; an organic light emitting layerformed on the first electrode, and a second electrode formed on theorganic emission layer, and wherein the dam includes a lower layer madeof the same material as the second interlayer insulating layer and anupper layer positioned on the lower layer and made of the same materialas the pixel defined layer an organic emission layer disposed on thefirst electrode; a second electrode disposed on the organic emissionlayer; a first inorganic insulating layer disposed over the secondelectrode; an organic insulating layer disposed over the first inorganicinsulating layer; a first dam comprised of a pattern of the pixeldefined layer disposed along an edge of the flexible substrate; and afirst groove disposed through the first interlayer insulating layerbetween the first dam and the edge of the flexible substrate, whereinthe first inorganic insulating layer does not cover over the firstgroove.
 2. The OLED display of claim 1, further comprising: a bufferlayer formed disposed on the flexible substrate , wherein theanti-overflowing groove is formed through the first interlayerinsulating layer and the gate insulating layer and exposes the bufferlayer and the semiconductor layer.
 3. The OLED display of claim 1,wherein further comprising: the dam includes a first dam and a seconddam positioned at both sides, having the anti-overflowing groovedisposed there between a second inorganic insulating layer disposed onthe organic insulating layer.
 4. The OLED display of claim 3, wherein:the dam further includes a first dam, a second dam, and a third damhaving the anti-overflowing groove disposed between the second and thirddam wherein the first inorganic insulating layer and second inorganicinsulating layer cover over the first dam.
 5. The OLED display of claim1, further comprising: an encapsulation layer positioned on thesubstrate and covering the pixel area, wherein the encapsulation layerincludes at least one inorganic layer and organic layer claim 4, whereinthe second interlayer insulating layer is made of an organic layer. 6.The OLED display of claim 1, further comprising: an anti-crack groovepositioned between the dam and the end of the substrate wherein thefirst dam is further comprised of a pattern of the second interlayerinsulating layer.
 7. The OLED display of claim 1, further comprising: asecond groove disposed between the first dam and the edge of theflexible substrate.
 8. The OLED display of claim 7, further comprising:a second inorganic insulating layer on the organic insulating layer. 9.The OLED display of claim 8, wherein the first inorganic insulatinglayer and second inorganic insulating layer cover over the first dam.10. The OLED display of claim 9, wherein the second interlayerinsulating layer is made of an organic layer.
 11. The OLED display ofclaim 10, wherein the first dam is further comprised of a pattern of thesecond interlayer insulating layer.
 12. The OLED display of claim 2,further comprising: a second inorganic insulating layer on the organicinsulating layer.
 13. The OLED display of claim 12, wherein the firstinorganic insulating layer and second inorganic insulating layer coverover the first dam.
 14. The OLED display of claim 13, wherein the secondinterlayer insulating layer is made of an organic layer.
 15. The OLEDdisplay of claim 14, wherein the first dam is further comprised of apattern of the second interlayer insulating layer.
 16. The OLED displayof claim 15, wherein the first dam is further comprised of a pattern ofthe gate insulating layer.
 17. The OLED display of claim 16, furthercomprising: a second dam comprised of the same layers of the first damis disposed between the first dam and the edge of the flexiblesubstrate.
 18. The OLED display of claim 17, wherein the second dam iscovered by the first inorganic layer and the second inorganic layer. 19.The OLED display of claim 18, wherein a third groove is disposed betweenthe first dam and second dam.
 20. The OLED display of claim 19, whereinthe first dam and the second dam are further comprised of patterns ofthe first interlayer insulating layer.
 21. The OLED display of claim 1,further comprising: a connecting member electrically connected to thesecond electrode.
 22. The OLED display of claim 21, further comprising:a second inorganic insulating layer on the organic insulating layer. 23.The OLED display of claim 22, wherein the first inorganic insulatinglayer and the second inorganic insulating layer cover over the first damand the connecting member.
 24. The OLED display of claim 23, wherein thesecond interlayer insulating layer is made of an organic layer.
 25. TheOLED display of claim 24, wherein the first dam is further comprised ofa pattern of the second interlayer insulating layer.
 26. The OLEDdisplay of claim 1, wherein the first groove disposed through the gateinsulating layer and the first interlayer insulating layer exposes aportion of a buffer layer disposed on the flexible substrate between thedam and the edge of the flexible substrate.
 27. The OLED display ofclaim 1, further comprising: a second dam comprised of the same layersof the first dam disposed between the first dam and the pixel area,wherein the second dam is completely covered by the organic insulatinglayer.